Method for making a battery pack

ABSTRACT

A flexible welding board for a battery pack, which is a polyester film or polymer with prepunched holes and a laminated nickel alloy or other metal or metal material. The polyester film with a suitable polymer adhesive or other adhesive includes a laminated nickel or other metal thereon. The nickel alloy or other metal alloy or metal is subsequently imaged with a pattern, and etched providing a flexible welding board for the welding of components of a battery pack, including the battery cells, electrical components and the electromechanical components which are spot-welded thereto. The entire process can be done robotically providing a battery pack which has electromechanical integrity between the battery cells, components, flexible welding board and the battery pack housing.

This is a continuation of Ser. No. 07/886,869, filed May 22, 1992, nowabandoned, which application is a Continuation-in-Part of U.S. Ser. No.07/618,454, filed Nov. 27, 1990, now abandoned, entitled "FlexibleWelding Board for Battery Pack," to the same assignee.

BACKGROUND TO THE INVENTION

1. Field of the Invention

The present invention pertains to a battery pack, and more particularly,a nickel cadmium battery pack, or battery pack with a nickel alloy,metal alloy or metal flexible welding board, which allows for thewelding of battery cells, electrical components and electromechanicalcomponents, including the battery cells directly to the flexible weldingboard. The welding is preferably by spot-welding.

2. Description of the Prior Art

In the past, battery packs, particularly nickel cadmium battery packs,have been assembled by hand where the batteries are spot-welded to eachother by flat straps, such as stainless steel or nickel. Then, thecontacts are placed into the battery pack housing, and the batteries areagain connected by spot-welding the flat straps to the battery contacts.Finally, the electrical or electromechanical components such asthermistors, resistors, capacitors and any other components areconnected along the process to the straps or the contacts, such as byspot-welding or soldering. This type of process is labor intensive, andtakes considerable time and motion by a group of individuals to assembleeach battery pack.

Prior art flexible circuits were sometimes not practical, as thecircuits could sometimes not be easily mass-produced, nor could theflexible circuits sometimes be easily spot-welded. Prior art flexiblecircuits were not able to include all of the components, including thebattery cells, the electrical components and the electromechanicalcomponents such as the battery casing contacts. Prior art flex circuitsdid not lend themselves to mass production for use in NiCad or othertypes of battery packs.

Prior art flexible circuits were usually a copper material on a polymer.Prior to etching of the copper material, the copper had to sometimes beprotected, such as by plating with a tin lead or a tin nickel. This wasan additional time consuming step which added expense and labor.

Prior art standard flexible boards require soldering metal weld tabs tothe board to allow battery cells to be welded to it thus adding expenseand labor.

The present invention overcomes the disadvantages of the prior art byproviding a unique and novel flexible welding board where all of theelectrical components and electromechanical components can bespot-welded to the flexible welding board such as a polyester board forsubsequent insertion into a battery housing or battery casing, therebyforming a battery pack. The elimination of the labor intensiveoperations of adding weld tabs prior to welding results in a significantcost savings, as well as allowing a more compact board design.

SUMMARY OF THE INVENTION

The general purpose of the present invention is a battery packing aflexible welding board of a nickel alloy or other metal alloy or metallaminated onto a deformable shape retaining polyester or polymer filmwith a co-extruded polymer adhesive or other suitable adhesive ormaterial therebetween for inclusion within a battery pack. Theelectrical components and the electromechanical components can bedirectly welded onto the nickel alloy or other metal alloy of theflexible circuit board with subsequent placement inside a polymer casingof the battery pack, thereby forming a battery pack. The flexiblewelding board lends itself to mass production, particularly silkscreening techniques, photographically imaged techniques, and etchingtechniques for forming the electrical circuit pattern on the nickelalloy or other metal alloy or metal which is laminated to the polymerfilm. The metal foil can also be any other suitable metal alloy ormetal.

According to one embodiment of the present invention, there is provideda flexible bare back welding board for a battery pack including apolymer film a polyester film or polymer film base with apertures formedat the welding locations, suitable co-extruded or other adhesives ormaterials, and a laminated nickel or other metal alloy or metal. Thenickel alloy or other metal alloy or metal can be silk screened, orlithographed on a laminated resist film applied to the metal withelectrical circuit patterns, etched with suitable chemicals, andsubsequently processed to provide a welding pattern of the nickel alloyor other metal alloy on the polymer or polyester film for subsequentelectrical and electromechanical assembly, including battery cells, andelectrical and electromechanical components to produce a battery pack.The battery cells, electrical components, electromechanical componentsand the flexible welding are positioned in a polymer casing, includingthe contacts which can be spot-welded to the flexible welding board toproduce the battery pack. The nickel or other metal alloy materialspot-welds like stainless steel, and is very desirable for spot-weldingas is the metal stainless steel.

Significant aspects and features of the present invention provide aflexible welding board for a battery pack, such as a battery pack whichcan be spot-welded.

Another significant aspect and feature of the present invention is aflexible welding board which is adaptable to robotic manufacturingprocesses and robotic welding processes. The nickel alloy or other metalalloy or metal material particularly lends itself to spot-welding.

A further significant aspect and feature of the present invention is aflexible welding board such as polyester composition which provides forthe attachment of electrical components, including battery cells,resistors, capacitors and thermistors, as well as electromechanicalcomponents such as battery pack contacts for battery chargers where thebattery pack contacts mount within the polymer casing of the batteryhousing and are spot welded directly to the flexible welding board.

A further significant aspect and feature of the present invention is aflexible welding board having nickel alloy or other metal alloy batteryinterconnection straps and at least two contacts adhesively secured to apolymer or polyester flexible base. The base is so dimensioned and thecontacts and straps so oriented and dimensioned such that automaticalignment of the straps and contacts with the battery terminals iseffected when the base is formed about a battery pack.

A still further significant aspect and feature of the present inventionis that the flexible welding board can be fabricated as individualboards on a continuous strip with discrete multiple circuit patternsformed thereon at spaced intervals. The strips with the boardstemporarily attached thereto can be coiled for continuous processing.The strips can be formed in a process line and will retain the formedshape. This feature is particularly desirable in facilitating theplacement of battery cells within the formed welding board.

Having thus described the preferred embodiments of the presentinvention, it is a principal object hereof to provide a flexible weldingboard for a battery pack, such as for a portable radio or any otherelectrical or electronic device.

One object of the present invention is a nickel alloy, other metal alloyor metal flexible welding board for use in a battery pack.

Another object of the present invention is a nickel alloy, other metalalloy, or metal flexible welding board which can be readily manufacturedby automated etching processes.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects of the present invention and many of the attendantadvantages of the present invention will be readily appreciated as thesame becomes better understood by reference to the following detaileddescription when considered in connection with the accompanyingdrawings, in which like reference numerals designate like partsthroughout the figures thereof and wherein:

FIG. 1 illustrates a plan view of a flexible welding board, the presentinvention;

FIG. 2 illustrates an end view of the flexible welding board;

FIG. 3 illustrates a front view of the flexible welding board aboutbattery cells taken along line 2--2 of FIG. 1, including two alternatingsize AA cells in place;

FIG. 4 illustrates a back view of a flexible welding board; and,

FIG. 5 illustrates an exploded view of a front view of the back half ofa battery pack, the flexible welding board with battery cells, and afront view of the front half of the battery pack.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a plan view of a bare back flexible welding board 10,the present invention, including a plus pad 12, a minus pad 14, andbattery straps 16a-16n, all of which are adhesively secured to apolyester base 18, as later described in detail. The battery straps16a-16n accommodate a plurality of cells, such as AA cells, by way ofexample and for purposes of illustration only, and not to be construedas limiting of the present invention. Any other size battery cell can beutilized. The battery cells can be alkaline, mercury, NiCad, or anyother suitable type of cells. The battery straps 16a-16n wrap around thealternating cells, and in this instance, provide a 15 volt disposablealkaline battery for an electronic product, such as a portable radiosuch as a Handie-Talkie FM radio, also referred to as an "HT". Anassembly of the cells and the bare back flexible welding board thenengages into a molded plastic housing. The large flat rectangularportions form the contact pad points through holes in the molded polymerhousing as later described in detail. The principals and teachings ofthe present invention can pertain to any other types of battery cells,and any other types of electrical and electromechanical configurations.The battery straps 16a-16n are spot-welded onto the ends of each cell,and the spot-welding occurs through holes in polyester film 18 to engageand make contact with the appropriate end of the cell, as laterdescribed in detail. Usually, it only takes two spot-welding electrodesto make contact, but in this instance, three or more spot-weldingelectrodes may be preferable for efficient electromechanical contact andfor the appropriate surface area contact for current flow between thebattery straps and the batteries. The metal battery strap material is anickel or stainless steel alloy or other suitable metal alloy. Thisalloy of nickel or other material is laminated to a polyester film of asuitable thickness with a suitable adhesive. Any suitable metal alloy ormetal can be utilized as well as any suitable base material such as apolymer base or any other type of base material as well as any materialtherebetween for sticking the numbers together.

FIG. 2 illustrates an end view of the flexible bare backed welding board10 including the polyester film 18, the adhesive which could be aco-extruded adhesive 20, and the battery straps 16a-16n. Two cells,having terminals at opposite ends, are appropriately positioned and spotwelded to the straps of the flexible welding board 10. A typical weld 19is made through the straps 16a-16n through the plurality of holes21a-21n in the polyester film 18. The dimensions are exaggerated toappropriately illustrate the teachings of this patent.

FIG. 3 illustrates a front view of the flexible bare backed weldingboard 10 engaged about battery cells of alternating size AA cells inplace. All other numerals correspond to those elements previouslydescribed.

FIG. 4 illustrates a back view of the flexible welding board 10 of FIG.2. All numerals correspond to those elements previously described,including the alternating battery cells.

FIG. 5 illustrates an exploded view of a front view of a battery pack22, including a back half 24. A flexible welding board 10 with thebatteries forming a battery assembly 26, and a front view of the fronthalf 28 of the battery pack 22. All numerals correspond to thoseelements previously described. The back half 24 of the battery pack 22is essentially a small, rectangular box. The front half 28 of thebattery pack 22 includes two holes 30 add 32 which provide forengagement of the terminal pads 12 and 14 of the flexible welding board10 with the contact fingers of a Handie-Talkie radio when the batterypack 22 is inserted into the battery compartment of the Handie-Talkieradio. Other electrical or electromechanical components can bespot-welded to the flexible welding board 10, such as battery contacts,thermistors, thermal activated switches, diodes, or any othercomponents.

MODE OF OPERATION

The flexible welding board 10 is manufactured by processes so that thewelding allay geometrical configuration remains on the polyester film 18after the processing steps. Representative processing steps are nowdescribed below.

1.a. The hole pattern for the bare backed board is first punched throughthe substrate film by use of a press, and a die constructed with shrinkallowances for the material built into the die.

1.b. The circuit pattern is either laminated with dry resist film, withrespect to the holes in the substrate film, or the circuit pattern issilk-screened onto the nickel alloy or other metal alloy or metal andthen processed in a conventional manner. Either method is an acceptableprocess for laying out the circuit pattern of resist material on thealloy.

2. The nickel alloy or other alloy or metal is then processed in asuitable processing station, and particularly lends itself to horizontalprocessing with a plurality of stations. What is advantageous is thatthe material can be done in a reel-to-reel processing fashion because ofthe steps of laying out the resist pattern onto the nickel alloy orother metal alloy or metal material, which can be repetitive or canchange on a long length of material, and then the material can be coiledat the input end and the output end of a processor.

3. The process station would include an etch chamber, a cascade rinsechamber, a fresh water rinse chamber, an inspection station, a spraystripping solution station for removal of the resist material, a freshwater rinse station, and a blower drying station.

4. The etch chamber uses a ferric chloride solution, which is acombination of ferric chloride and hydrochloric acid. Any other suitableetching solution is also acceptable. This particularly lends itself toetching of the nickel alloy or other metal alloy or metal and isadvantageous because the ferric chloride etching solution isinexpensive, environmentally and economically preferred, and readilyetches the nickel alloy or other metal alloy or metal. Any suitablecaustic solution can be used to remove the resist over the welding boardpattern which remains after the etching away of the nickel alloy orother alloy which was not coated with resist. After processing, theflexible welding board can be cut apart, such as on a paper cutter, orpunched apart such as on a punch press. Alternatively, individualwelding boards fabricated in form and subsequently removed afterprocessing. The teachings of the present invention include a process tomanufacture product of a flexible welding board, which can be for largesized battery packs, such as for HTs, to small sized battery packs, suchas for Flip-Phones.

The product of the flexible welding board 10 of FIG. 1 is manufacturedby the new and novel recognition that the nickel alloy or other metalalloy can be adhesively secured to the polyester film 18, which can theninclude spot-welded electrical or electromechanical components,including but not limited to the components selected from the group of:battery cells, resistors, capacitors, thermal cutouts, thermistors,diodes, jumper wires, battery contacts and any other electrical orelectromechanical components.

Various modifications can be made to the present invention withoutdeparting from the apparent scope hereof.

We claim:
 1. Process for producing a battery pack comprising the stepsof:a. providing a polyester film; b. punching holes in said film; c.laminating a metal or metal alloy on said film; d. forming an electricalcircuit pattern from said metal or metal alloy with portions of saidcircuit pattern overlying said punched holes; e. providing at least twobatteries having terminals at opposite ends of each of said batteries;f. deforming said polyester film so that the terminals of said batteriesengage said circuit pattern at said punched holes; and g. welding saidcircuit pattern to said terminals to thereby electrically interconnectsaid batteries.
 2. The process of claim 1 wherein the step of laminatingincludes adhesively bonding said metal or metal alloy to said polyesterfilm.
 3. The process of claim 1 wherein the circuit pattern is formedby:a. silk screening an etch resist of an electrical circuit pattern onsaid metal or metal alloy; b. etching away unprotected metal or metalalloy; and, c. removing said etch resist to expose said electricalcircuit pattern.
 4. The process of claim 1 wherein said circuit patternis formed with two discrete terminal pads to facilitate electricalconnection to an external electrical device.
 5. The process of claim 4further including the steps of:a. providing a housing for said batterypack having two apertures; and, b. inserting said battery pack into saidhousing with said two terminal pads exposed through said apertures.